Phytosterol organic acid esters: Characterization, anti-inflammatory properties and a delivery strategy to improve mitochondrial function

Phytosterol organic acid esters are important food resources and the components of biomembrane structure. Due to the lack of extraction and synthesis techniques, more research has been focused on phytosterols, and the research on phytosterol acid esters have encountered a bottleneck, but phytosterol acid esters confer substantial benefits to human health. In this study, stigmasteryl vanillate (VAN), stigmasteryl protocatechuate (PRO) and stigmasteryl sinapate (SIN) were prepared through the Steglich reaction. The processes are promotable and the products reach up to 95% purity. In addition, their stability was evaluated by differential scanning calorimetry and thermogravimetric analysis. HPLC analysis revealed an enhancement in water solubility after esterification with phenolic acid. In an in vitro digestion model, the bioaccessibility of stigmasteryl phenolates was significantly higher than that of stigmasterols (STIs). Regarding the anti-inflammatory properties, VAN, PRO, and SIN exhibit superior effects against TNF-α induced pro-inflammatory responses compared to STI. All stigmasteryl phenolates supplementation increased the ATP production, the basal, and maximal oxygen consumption rate in mitochondrial stress test. Overall, we present a synthesis method for stigmasteryl phenolates. It will contribute to the development and research of phytosterol acid ester analysis, functions and utilization in food. Moreover, the nutrient-stigmasterol hybrids tactic we have constructed is practical and can become a targeted mitochondrial delivery strategy with enhanced anti-inflammatory effects.

Regulating effects of phytosterol esters-loaded emulsions stabilized with green tea polysaccharide conjugates and Tween on lipids in KKAy mice

Phytosterol esters (PSE) have been shown to have cholesterol-lowering effects, but their insolubility in water limits their applications. Green tea polysaccharide conjugates (gTPC) have hypoglycemic and emulsifying effects. To address lipid dysregulation in diabetic patients, we developed PSE-loaded emulsions stabilized with gTPC and Tween-20 (gTPC-PSE emulsions) and evaluated their physicochemical properties. We subsequently investigated the lipid-regulating potential of these emulsions to in KKAy mice. The KKAy mice were randomly assigned to eight groups: the model group, the Lipitor (10 mg·kg^-1)-acarbose (30 mg·kg^-1) combination group, two gTPC groups, two PSE groups, and two gTPC-PSE groups with a 1:2 mass ratio of gTPC to PSE. The administered doses were 90 and 270 mg kg^-1, respectively. Administration of a 270 mg·kg^-1 dose of gTPC-PSE emulsions led to the most significant effects including increased levels of liver and serum high-density lipoprotein cholesterol (HDL-CH), reduced serum leptin and insulin, and improved liver superoxide dismutase (SOD) and reduced malondialdehyde (MDA). In general, gTPC and PSE demonstrated a synergistic effect on lipid regulation in mice. Our results indicate that gTPC-PSE emulsions hold potential as a nutritional intervention for diabetes by modulating lipid levels.

Deacidification of high-acid rice bran oil by the tandem continuous-flow enzymatic reactors

Rice bran oil (RBO) contains a variety of nutrients, but the high acid values largely hinder its processing into edible oil. Thus, the tandem continuous-flow reactors are proposed and developed for the enzymatic deacidification of RBO and simultaneous production of functional oils. The results indicate that the Candida antarctica lipase B (CALB) immobilized on the hydrophobic ordered mesoporous silicon (OMS-C₁₈) increased 6.6 times of the catalytic activity and improved at least 20 ℃ of temperature tolerance compared to the commercial Novozym 435. The tandem continuous-flow enzymatic reactors removed 91.4% of free fatty acid and increased 9 and 12 times of phytosterol ester and diacylglycerol in RBO, respectively. Moreover, the retention rate of γ-oryzanol was at least 40% higher than that obtained by traditional alkali refining. This study provides an effective and sustainable method to continuously convert the low-value RBO into value-added products, which brings huge potential to cleaner industrial production.

An efficient and robust continuous-flow bioreactor for the enzymatic preparation of phytosterol esters based on hollow lipase microarray

In this study, a continuous-flow bioreactor packed with well-organized lipase microarrays was developed for the sustainable synthesis of functional lipid-phytosterol esters (PEs). Hollow mesoporous silicon spheres with a suitable pore size were prepared for lipase immobilization, and the hydrophobic modification endowed the lipase with excellent catalytic activity and stability. The results showed that the condensely packed lipase microarrays offered large specific surface areas and guaranteed the thorough interaction between the lipase and substrates in the continuous-flow bioreactor. Meanwhile, the substrate could pass through the reactor at 1 mL/min with a high conversion of 93.6% due to the hollow structure of the packing spheres. Moreover, the reactors were able to produce 1564 g PEs/g catalyst in a continuous 30-day processing period, which set the highest records for PEs synthesis. This sustainable and highly-converting flow system provided a feasible path for scale-up production of PEs in the food processing area.

Acyl moiety and temperature affects thermo-oxidative degradation of steryl esters. Cytotoxicity of the degradation products

Phytosterols and their esters are often used as functional ingredients in food products due to its lowering blood cholesterol properties. Products containing phytosterols and its esters are recommended for direct consumption, cooking, baking and frying, however during food preparation it is possible thermo-oxidative degradation is possible. Unsaturation of fatty acid present in steryl ester may further stimulates degradation. Free stigmasterol degraded faster than its esters, even with linoleic acid attached. The highest amount of degradation products was observed for free stigmasterol, followed by esters with linoleic and oleic acids. Polar dimers were fund in all heated samples, although for free stigmasterol heated at 60 °C were not detected. Whereas non-polar dimers were observed only in heated stigmasterol. Degradation of esterified stigmasterol generated degradation products with lower cytotoxicity.